The present invention relates to a crusher for demolishing building walls, roadbeds, bridges and so on.
FIGS. 8A-B shows a conventional crusher mounted on the free end of an arm of a self-propelled civil engineering machine. This crusher comprises a bracket 60 pivotally mounted on the free end of the arm 54b of the civil engineering machine by means of a pin 65, a frame 61 rotatably mounted on the bracket 60 and having a crushing jaw 62, and a movable arm 63 having its rear end pivotally mounted on the frame 61 by mean of a pin. 64. An object X placed between-the arm 63 and the crushing jaw 62 is crushed by pivoting the arm 63 with a driving cylinder (not shown). Otherwise the object X is crushed by swinging the bracket 60 with the object gripped.
This crusher has its crushing jaw 62 integrally formed on the end of the frame 61. Thus, provided the arm 54b is fixed, its angular working range within which the jaw 62 and the movable arm 63 can crush an object X is equal to the angle by which the bracket 60 can be swung about the pin 65 by a cylinder 56 mounted on the arm 54b i.e. from the position shown in FIG. 8A to the position shown in FIG. 8B. In FIGS. 8A and 8B, the line a-a' indicates the axis of an object X clutched by the crushing jaw 62 and the movable arm 63.
FIG. 8C diagrammatically shows the above angular working ranger .alpha..sub.0. In order to crush an object X that is disposed out of this range, the entire machine has to be moved and/or the arm 54b has to be swung. This arrangement drastically reduces the working efficiency. Particularly, when the work is difficult due to limited space, e.g. on a bridge.
An object of the present invention is to increase the working range within which the crushing jaw and the movable arm can crush an object.
Another object is to reduce the necessity of moving the civil engineering machine itself to a minimum and to increase the efficiency of the work.